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.\" 1.0 of the CDDL.
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.\" Copyright 2016 Joyent, Inc.
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.Dd Sep 16, 2016
.Dt USBA_HCDI_DUP_ISOC_REQ 9F
.Os
.Sh NAME
.Nm usba_hcdi_dup_isoc_req
.Nd duplicate an isochronous request
.Sh SYNOPSIS
.In sys/usb/usba/hcdi.h
.Ft "usb_isoc_req_t *"
.Fo usba_hcdi_dup_isoc_req
.Fa "dev_info_t *dip"
.Fa "usb_isoc_req_t *usrp"
.Fa "usb_flags_t flags"
.Fc
.Sh INTERFACE LEVEL
.Sy Volatile -
illumos USB HCD private function
.Pp
This is a private function that is not part of the stable DDI.
It may be removed or changed at any time.
.Sh PARAMETERS
.Bl -tag -width Fa
.It Fa dip
A pointer to the HCD driver's
.Sy dev_info
structure.
.It Fa usrp
A pointer to the USB isochronous request which will be duplicated.
.It Fa flags
.Bl -tag -width Sy
.It Sy USB_FLAGS_NOSLEEP
Do not block waiting for memory.
If memory is not available the allocation will fail.
.It Sy USB_FLAGS_SLEEP
Perform a blocking allocation.
If memory is not available, the function will wait until memory is made
available.
.Pp
Note, the request may still fail even if
.Sy USB_FLAGS_SLEEP
is specified.
.El
.El
.Sh DESCRIPTION
The
.Fn usba_hcdi_dup_isoc_req
function is used to duplicate an existing isochronous request,
.Fa usrp .
.Pp
When the USBA framework initiates an isochronous in transfer with the
.Xr usba_hcdi_pipe_isoc_xfer 9E
entry point, it is the HCD driver's responsibility to receive the
periodic data from the pipe.
When there is data available, the HCD must duplicate the original isochronous
request and copy the available data into the request structure's
.Fa isoc_data
member, before handing over the request structure to the USBA framework
by calling the
.Xr usba_hcdi_cb 9F
function.
.Pp
In addition to duplicating the request, it is the callers responsibility
to increase the pipe handle's request count.
For more information, see
.Xr usba_hcdi_pipe_isoc_xfer 9E .
.Pp
The
.Fa dip
argument should correspond to the HCD driver's
.Sy dev_info_t
structure.
The
.Fa usrp
pointer should correspond to the initial isochronous request.
The
.Fa flags
member must be appropriate for the context.
If
.Dv USB_FLAGS_SLEEP
is passed while in interrupt context, then this function may fail.
.Sh CONTEXT
The
.Fn usba_hcdi_dup_isoc_req
function may be called from
.Sy user ,
.Sy kernel ,
or
.Sy interrupt
context; however, when in interrupt context, the value of
.Fa flags
must be
.Sy USB_FLAGS_NOSLEEP .
.Sh RETURN VALUES
Upon successful completion, the
.Fn usba_hcdi_dup_isoc_req
function returns a pointer to a duplicate isochronous request.
Otherwise,
.Sy NULL
is returned to indicate that the request could not be duplicated.
.Sh SEE ALSO
.Xr usba_hcdi 9E ,
.Xr usba_hcdi_pipe_isoc_xfer 9E ,
.Xr usba_hcdi_cb 9F
